The concept that an invasive species from a more species diverse region is more likely to survive in a new region was proposed by Charles Darwin in 1859. Dov Sax of Brown University and Jason Fridley of Syracuse University have proven Darwin to be correct by a new analysis of invasive species that includes the paleontological record and the present.
The new “Evolutionary Imbalance Hypothesis” is actually a restatement of Darwin’s concepts with proof. The researchers used phylogenetic diversity as a proxy measure of the intensity of competition, environmental stability, habitat age, and population diversity in three regions of the world where invasive species have flourished. The researchers examined plants and animals in Eastern North America, the Czech Republic, and New Zealand.
Just as Darwin predicted, the more robust species that come from an environment that has a higher number of species and more competitions were more likely to survive and thrive as invaders in new territory. The fossil record also proves the point. When the Bearing Land Bridge disappeared the marine mollusks had a new path between the Atlantic Ocean and the Pacific Ocean. The presence of mollusks all over the world that at one time in the ancient past only inhabited the Arctic regions is evidence of the validity of the concept.
The new model is espoused as a warning to ecosystem managers. The Evolutionary Imbalance Hypothesis can be used as a predictor of the likelihood that an invasive species will thrive in a new environment. Foreknowledge may prevent the extinction of some species that developed in a more peaceful environment than the invading species.
